Appareil hydraulique de commande à distance

547,650. Hydraulic remote controls. HYLAND, C. Nov. 15, 1941, No. 14719. [Class 69 (ii)] A hydraulic remote control apparatus, which is especially applicable for operating a soot blower by means of a rack-and-pinion and step-up gearing connected to a hydraulic ram 1, comprises a pump 11, control valve 6 which controls the supply of pressure fluid to pipes 3, 4, 5 leading to the cylinder 2 in which works the piston 10 of the ram 1. The piston 10 may be moved to either end of the cylinder 2 or stopped in an intermediate position, or it may be reciprocated within limits corresponding to intermediate positions in which the piston comes to rest at either side of the intermediate part 9. An indicating device 27 is employed and is operated by a piston 25 and cylinder 16 which is in series with the pipe 3. The capacity of the cylinder 16 is less than that of the cylinder 2 so that when the pipe 3 is connected to pressure or exhaust the piston 25 reaches the end of its cylinder before the piston 10 and excess liquid then passes through a byepass passage 19, or 20 and a non-return valve 21, or 22. The piston 10 may be made to assume more than one intermediate position by providing extra ports in the cylinder 2. The exhaust pipe 15 leads to a tank connected to the pump 11.